Re: [Xen-devel] [PATCH] tools/kdd: don't use a pointer to an unaligned field.

[Roger Pau Monne]

On Fri, Mar 10, 2017 at 10:10:57AM +, Tim Deegan wrote:
> The 'val' field in the packet is byte-aligned (because it is part of a
> packed struct), but the pointer argument to kdd_rdmsr() has the normal
> alignment constraints for a uint64_t *.  Use a local variable to make sure
> the passed pointer has the correct alignment.
> 
> Reported-by: Roger Pau Monné 
> Signed-off-by: Tim Deegan 

Acked-by: Roger Pau Monné 
Tested-by: Roger Pau Monné 

Right, I got messed up while manually calculating the offsets by hand... Thanks
for fixing this.

Roger.

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[Xen-devel] [PATCH] tools/kdd: don't use a pointer to an unaligned field.

[Tim Deegan]

The 'val' field in the packet is byte-aligned (because it is part of a
packed struct), but the pointer argument to kdd_rdmsr() has the normal
alignment constraints for a uint64_t *.  Use a local variable to make sure
the passed pointer has the correct alignment.

Reported-by: Roger Pau Monné 
Signed-off-by: Tim Deegan 
---
 tools/debugger/kdd/kdd.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/debugger/kdd/kdd.c b/tools/debugger/kdd/kdd.c
index 70f007e..1bd5dd5 100644
--- a/tools/debugger/kdd/kdd.c
+++ b/tools/debugger/kdd/kdd.c
@@ -710,11 +710,13 @@ static void kdd_handle_read_ctrl(kdd_state *s)
 static void kdd_handle_read_msr(kdd_state *s)
 {
 uint32_t msr = s->rxp.cmd.msr.msr;
+uint64_t val;
 int ok;
 KDD_LOG(s, "Read MSR 0x%"PRIx32"\n", msr);
 
-ok = (kdd_rdmsr(s->guest, s->cpuid, msr, >txp.cmd.msr.val) == 0);
+ok = (kdd_rdmsr(s->guest, s->cpuid, msr, ) == 0);
 s->txp.cmd.msr.msr = msr;
+s->txp.cmd.msr.val = val;
 s->txp.cmd.msr.status = (ok ? KDD_STATUS_SUCCESS : KDD_STATUS_FAILURE);
 kdd_send_cmd(s, KDD_CMD_READ_MSR, 0);
 }
-- 
2.7.4


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